Digital documents often need to be resized to fit the display whereon the document image is intended to be shown to the user, such as mobile phones displays, camera and video displays, PDAs, and the like. Document images can be resized by a cropping or scaling technique. Cropping works reasonably well for shrinking images if there is only one region of interest in the document. Scaling works reasonably well for shrinking images containing low frequency information. However, scaling can be of limited value because scaling tends to be uniformly applied to the image resulting in information loss. With proper region identification, cropping may be preferred over naïve scaling. Naïve cropping can be problematic because important contextual information may be removed from of the document.
Document resizing is a non-trivial process that involves a trade-off between many parameters such as efficiency, smoothness, and sharpness. As the size of a document is increased, the pixels which comprise the image become increasingly visible and distort the content. Enlarging an image is less common because it may not be possible to discover any more information during the resizing operation to put into the image than which already exists and image quality of the end product may suffer as a result. Content aware image resizing can yield more pleasing results, especially when an image needs to be anamorphically resized. However, existing methods such as naive removal of content have limitations that can lead to undesirable artifacts such as uneven spacing of text.
Images of documents tend to be different from pictorial images. The former tend to contain various objects such as text, pictures, graphics, and the like, arrayed over a background which includes white space and other uniformly colored areas. Pixels in uniform background regions make excellent candidates for removal as their removal tends to introduce fewer changes in the document content. However, naively removing pieces of background from the document can impact the document's visual balance and proportionality.
Accordingly, what is needed in this art are increasingly sophisticated systems and methods for resizing documents which adaptively remove background content from a document while effectively maintaining an overall visual balance of the background of the document.